Rotary hook sewing machine thread case



April` l-l, 1939. J. D. KARLE ROTAY HOOK SEWING MACHINE THREAD CASE Filed Ap'ril 14, 1938 1 2 Sheets-Sheet l arten/Maj Apgil 1l, 1939.

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2 Sheets-Sheet 2 J. D. KARLE ROTARY Hoox SEWING MACHINE THREAD CASE Flled Aprll 14, 1938 kroamed Apr. 11,1939

- "UNITED STATES, PATENT, A OFFICE f ww . John nxnienonuorimmrsmnorio The Singer Manufacturing Company,

beth. N. 1., a corporation# New Ierse! appuoaoon Ani-l1 is-iasasorw No. com: 'i clams. (ci. 11s-sn) 1 Thisl invention relates' to sewing machine thread-case devices such as are commonly used .with needle-thread loop-takers of the rotary hook type disclosed, for example, in U. S. Patents No.

5 1,125,669, dated Jan. 19, 1915, No. 1,995,278, dated Mar. 19, 1935, and No. 2,085,699, dated June 29,

' Thread-cases ofthe type disclosed in the'above cited patents comprise acup-shaped carrier sec-- .10 tion having a center post or arbor and a periphv eral bearing rib which is journaled in a raceway in a cup-shaped rotary hook member, such car-v rier-section having a rim flange formed with a yrotation-restraining notch which is loosely entered by a tongue on a stationary rotationrestraining member mounted on the bed of the hnachine. 4The bobblnis housed in a cylindrical bobbin-case which removably iits in the carriersection and carries a bobbin-thread texsionspring and a manually r'eleasable latch engaging the center-post of the carrier-section. Rotary hook and thread-case devices of the general type discussed above have long been known and used Y and, in the many years of their prominence in the Ysewing machine art, they have engaged the talented efforts of the best sewing'inachine in-l ventors and improvers, ywhich efforts have been lavishly expended inbringing these devices .upto thehigh state of developn'ent and perfection of performance knownat `the present time. This process of development `has been painfully slow. 7

as the pathsof approach to the perfect hook and thread-case were vbeset with serious diioulties too numerous to mention' for, as often happens, the elimination of one diillcultyusually introduced other difliculties to be contended with, so that forward steps in the art were often a matter of compromise or the balancing of one consideration against another, so as to get a superior all around 4I)v perfomance with a minimum of disadvantageous conditions.

A rotary hook and thread-case device at this high state of perfection is exemplified in the Kessler Patent No. 2,085,699, of June 29, 1937. g Y It is thecumulative result of the eiforts of sew,-

ing machine inventors overa period o! upwards of seventy-five years.

It has all this time been chief drawback of the lock-stitch sewing machine is the necessity of providing fa wound bobbin of under thread'over whichv rmust bevsbreadand'passedby vthe The bobbin ofunder thread 'reqinresfleqllelit sa replenishment, which necessitates each-loop of needle v A thread, projected through the work by the needle.:

stoppage oi the machine It goes without saying that the larger the bobbin is, the less frequently it will require replenishment, so that it has been Inaled. Enlargement of the' raceway diameter is found to greatly increase heating diiilculties( at the high operative speeds demanded of the modern lock-stitch machine. Moreover, enlargement v of the thread-case results in enlargement of the 15 size to which each needle-loopmust be drawn out or expanded by the rotary hook in order to pass it about the thread-case. As the take-up device must pull up .each expanded needle-'loop after it is interlocked withthe bobbin-thread to set the 20 stitch, it follows that in the making of each stitch,

a length of needle-thread approximately equal to the length of thread in the expanded needle-loop must reeve through the eye of the needle. This' repeated reeving of the needle-thread through 25 the eye of the needle is highly' destructive as it tends to fray and weaken the thread. Hence, the larger the bobbin-case, the greater'the destructive reeving action at any given point in the thread-v supply to the needle. 30'

points of superiority over its predecessors or sacriil'cing any of. its superior operative characteristics,

so gly arrived at by prior inventors in the sewing machinev art.` 4o

With the above and other objects in view, as willhereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forthand illustrated in the accompanying drawings of a preferred embodi` 45 ment of the invention, fromV which the several featres of the invention and the advantages attained'therebywill thoseskilled in the art.

Oftheaccompanyingdrawinsalg. 1isa50 front facerelevation of a sewing machine rotary hook and-threa'd-case embodying the invention. Fig. 2 is a right side elevation of the parts shown Fig. l-with the rotary hook beak' turned to a point''wt pastloop-taking position Eig. 3 is a section on the line 3-3, Fig. 1. Fig. 4; is a'section ofthe thread-case on1y, on the line 4 4,

Fig'. l. Fig. 5 is a front face view ofthe main cupfshaped section of the thread-case. Fig. 6 is a rear face view of the same. Figs. 7 and 8 are Fig. 9 is a face perspectiveviews of the same. view of the rotary hook member in vwhich the thread-caseis' journaled. Fig. 10 is a perspec-4 tive view of the rotary hook member. Figs. 11 l0 and 12 are respectively, front face and left edge views of the cap-section of the thread-case. Fig:

13 is a bottom edge vie'w of the cap-section shown in Fig. 11. Fig. 14 is a perspective view 0f the cap-section of the thread-ease.. Fig. 15 is a perls'spective view of the'cap-section of the threadcase together with a bobbin of thread. Fig. 16 is a horizontal diametrical section ofl the parts shown in 15. ZFig. 17 is a disassembled per- 'spective view of the latch-elements carried by the 20 thread-case cap and Fig. 18 is a section through the thread-case substantially in the plane of the inner face of the thread-'case cap or on4 the line I8I8, Fig. 4.

` I represents the reciprocatoryneedle of a sewing machine having the usual vthroat-plate 2 v wall of a section ci.' he raceway E in Ywhich the peripheral bearing rib II of the stationaryy thread-case is journaled. 'I'he gib 91s pointed at one end to constitute a-loopcontrolli'ng tail I2 onto which the castneedlethread-loop' I3. Fig. 2,

is dravmfrfmnV the nookfbeak 1 by the usual iakeup device, not shown, to prevent the lloop i3 freintwisting and'kinking and to hold it ofl.' of the {thread-case bearing rib I las expninea inthe said Kessler Patent No. 2,085,699. i ,Y 45. 'I'he stationary thread-case, Fig. 4, in which the present invention' is-embodied comprises the main section4 I4, Figs. 5, 6, 7 and 8, and the can section 30,"Figs. 11 to. 16, inclusive. 'The main section I4 oi the thread-case is of cylindrical cup shape and has at its' rim the usual outwardly extending needle-loop guard-liange I9 which is preferably notched at K oi the said Kessler Patent No. 2,085,699. 'I'heA main Isection I4 of thethread-case carries the` 5p; peripheral bearing rim I'I which has a gap in its upper portion tn prov'idethe usualfneedle-loop detaining'shoulder I9 andneedle-loop confining shoulder I9 the iun'ction'sof which are well un'-J derstood by those skilled in the art and need not 'e0 be here dweltupon. The iiange I6 is also formed usual -rotation-restraining notch 20 with the Av which is looselyv entered by the tongue 2|,on the usual rotation-restraining bar 2 2 common to rotary'hook lock-stitch sewing machines. 35 IThe main section I4 vof the thread-case-has a inner cylindrical side wall 23 and an inner ila l end wall 24 which supports lthe axial cen "r post 25 grooved at 29 for alatch member to be referrea to. The rim of the cup-shaped mainsta- 70 tion 'I4 oi? the thread-case is cut away at one side' A astar'astheperi bearingrib II toform a. gap 21 which hasa; special purpose in the present arrangement. v'I'he inner cylindrical wall '23 of the thread-case section I4 is counterbored or enf 76 larged in diameter at 2l to receive the short thin' I'I imaccordance withthe disclosure skirt portion 29 of, the cap-section 39 which re movably closes the outer end of the main section I4.of the thread-case and has a tubular arbor 3| lengthened skirt portion '33 is the tension leaf spring SII the pressure of which upon the bobbinthread '36 may be regulated by manipulation of the tension-regulating screw 36 in the usual manner. The shoulder 31 near the base end of the 20 tension-spring 34 together with the shoulder formed by the free end V38 of the tension-spring 34 extend into the gap 21 in the cylindrical wall of the main thread-case section I4 and rotatively positionV the cap-section relative to the main sec- 25 tion, as shown in Fig. 18. In other words, the cap-section can only be applied to the main section with the shoulders 31 and 38 juxtaposed with the shoulders at theends of the gap 21. An imi portant feature gained by'the present improve- 30 ment is this, that the radius-oi curvature of thev inner Awall of the cap skirt"33 is as great as that of the inner cylindrical wall 23 of the main sec` tion. Hence a, bobbin can be accommodated which has ilanges substantially as large in radius 35 as the radius of curvature of the inner wall 23 of the main section of the thread-case; the skirt oi.' the cap-section being no longer a limiting factor asv to bobbln ange diameter. By these meansI have increased the capacity of the bobbin of the 40 thread-case of the Kessler Patent No. 2,085,699 at least 20% without increasing the overall size` of the thread-case or increasing the diameter oithe thread-case bearing rib and without sacrifice vof any'of the improved operative characteristics of 45 the hook and bobbin-case devicefasdisclosed in\ said Kessler Patent No. 2,085,699.

The cap-section 30 is fltted with the usual manually operated latch-bar 39 which slides in a diametrical slideway 40 in the face of the cap-sec- 50 tion 3,0 and isbiased to latching position by theA spring 4I lwhich engages the lateral extension 42` of the latch-bar. 'I'he latch-bar has a hole 43 in it'to admit the grooved end of -the center post 25 of the mainI thread-case section, afterwhich th'e 55A bar is slid endwiseby' the spring" to carry the curved edge-portion of the bar at the hole 43 into the. groove'26 lof the center post 25. The latchbar 39,pivota1ly carries the finger-piece or lever u which ams inner end may be caused to imsov "Dinge upon the' shoulder at one side of. a square hole 49 in the cap-'section 30,'which shoulder affords a fulcruin for the lever 44 to withdraw the latch-bar v39 from locking 'engagement with the grooved'center cap-section to gain access-dao the bobbin 32. The Alatch-bar has at one end the usual curved bobbin-flange-gripping extension 45 which enters the notch-46 in theange I6 .of the main thread'- case section, after the cap-section has been applied to the main. section and locks the capsection against-rotation relative to the lmain section independently of the initial lpositioning shoulders .31 and 38previ0lisly described.

The longer skirt portion `3 3 of 'thecap-section. 7.5

post 25 forv removal oi' the 65 y alzados' 3 whiehcarriesthethread-tmslouspringllis having'alesmmtalevlindrilakirtporonat, formed with the threading'slotfll leading'to the onesidebrldging the'cut-awayportion of the rim thread exit hole Il, Fig. 14.' under the' free end 'ofthethread-casebodLandatenslonlf-spring ofthetension-spring'ILV Y l Vl 'I'hebobbinllmaybeapiilieasusuahtothe ternalradiluofcurvatmeofsaidcap-skirtpor- 5 tubulararbollofthecallandthe -tionbdngaslarge`asthatotthecylindcal two applied tothe main section,.as' thread-case to home a' hobbin-thread mass of readily as heretofore. y sin with a given diam- Y, The thread-case body is preferably chamfered eter of hook-rama; w 1o adjacent' its inner edge at Il, Figs. tand 6, to I4. The with a cup-shaped rotary 10 provide the needle-loop immer",aiuiirx hook-body having a circular raeeway Aand cut closed in the Kessler U.' AS. Patent 'No.'1,995,278, away at one side to form a. loop-taking beak', of dated 19, 1935, to facilitate an earlycstins a cylindrical cup-shaped thread-case body havqf the needle-loop 'onto the back face of the ingo.: its rimn om mains 15 thread-case, as explained in s aid last mentioned loop goud-llame. said "thread-case body having 16 -Kessler patent. j lheshrtskirtportionllofthethread-se andanaxinlpostsmmorxodbysaidinnorend cap-Section guards, `om 0I the bobbln-nses, as v wnmsoi'd thread-ease body also having oA peupli- 'shown'in Fig. 15, so that the cap-section withthe al bem-ing me and theme14 2o bobbinmdy be held dans rim in the angers or end m of such m, ma, hmm/,m1, M zo one handwhile the .operator dran' the lzpobbin-v n l man k 'fwd thread; l thread :s into the threading slof; n and to anni 82121, bdmmwmtf: mamy position in the hole Il and out under the` 'free Y i ond of the vmision-spring u, ineoobbin s: boing s f s am bem rn "11d mmmmred freetoturnonthe-arbor 3| duringthe manual in thmimngmnm'mch cames the 25* threading operation. In other words, because of needle'lplmm@ mwen te' the protesting skin: za, the porcs shown in mns movbly am the. Fmr and 0f sd *11mm-Se may be readily held for tno threading operation and hvlnr www' arbor lidblv #mns Seid \\\,witho'ut interfering with the free rotation of the f POSt. a releasable Mh Carried by said cap und bobbinll on thearbor Il. j Y

Havinginu's'set forth the datore of the inven- Skirt-110mm reived in ,themunterbore in the tion, `whntr claim hereiisis: rim 0f Said thread-se body. said skirt-portion I 1. A thread-case for rotary hook lock-stitch being'lengthened at one side to bridge the cutsewing machines comprising a @p shaped main away portion of the rim of the thread-case body,

section and a substantially ular cap-section, and tension-$911118 mounted 0n the longer 35 l'said cupfsndped main section hdving o periph Skirt-Portion ofsaid ihrem-case can. eral bearing rib and a cylindrical inner side wall 55- 'Ifhe combination with a IOtary hook-body which is counterbored in the rim portion thereof, having a loop-taking beak, of a stationary threadthe counterbore portion of saidmain seetion ex- Case `journaled in said 'rotary hook-body and o engaging said post, said "cap having -a short a0' 40 oluding anon-counterbored portion underlap'ping oomprisinga main section having an 40Y t'erbore in said main section, and manually op- 'tion' closing the open end of the main section. erable means ,for releasably latchingsaidsections; a b obhin-thread -spring and a manually -together. i operable latch each earriedby the cap-section. 45

l2. A thread-case for rotary hook mok-stitch said latch said center post, said capsewing machines compri-Sins a cup-shaped main section having a tulmlnr arbor slidnbly ntting section and 'asubstantlally oircularcap-section. said center post and atalfcylindrioal said cup-shapedmain sectionhavinsape'iphrl o skirt-portion on which said tension-spring is bearing riband a cylindrical inner Side will mounted, said skirt-portion having an inner 50 which is eounterboredin the radlusof curvature as great as that of the innerY the colmterborednortion oisidmainwction exa. cylindrical nnof the mun section of the cludins a. non-coimterbore portion underlappins thread-case, the rim of said main section being saidperlpheral saidcapsectlonhavcutaway at one side to reedve said segmental.- ing a short skirt portion 'received in the counterskirt-portion and tension-spring which serve td 55 bore'insaid Ymain section, and releasrbtatively locate the dpieeiionnpon thej main able means for latching said sections together. section' of the thread-case.

0 andcutawaylat onesidetoIOrmaIoopLtaHng main nlp-shaped section havingatits rim an beak, of aY cylindrical cup-shaped -thrd-onso. outwardly extending needle-loop mind-aange. body having at-its rini an'outwardlyextending said-main section also-having aninner end`wall needle-loop goud-moge, said thread-embody nn inner ylindrionll sido nn ,and an um post -shavlnsaninnereni-,wllcrlindrllinneride supportedbysnidmnerendwnnsnidmnnsoo- Waumdm m'mmmed Mmmm. tion also havinga peripheral bearing e119 Wim said thrmmeby 15 um! saidilangeandendwalLwhichbeal-ingiseomthemefmd'fdmm'mm toryhookwlthhionuatobe mornnof `is oomplementaltothebearingmaidhook-body, und'. Dtherimofsaidthread-caaebdngmltawayatmdmmbdngmamtone m one sldeasfarass'aiperipheralbearinga J .Y thread-case-eap removsblyoosingtheouterend 'mmte'mlfdmthemnmgmmnv'mch of said thread-dono ond having o nibuinr arbor @flies wld sund-11eme. I thread-we cop-See- 'slidnblyntting said post. areleasablelatoh csrtionremovahlyolosingiheonmutereni ofsoid. iriedbysaidcapandengagingsaidposgmdcgp `mainsee'tionandvlhavngatubulin-arborslidably- 75Y A nissnes l y Y. A fittingl seid post, a reileasable latch te ed by ardgangefxi rim-portion of the side weil of said cap-section and ensa'sins said poot, seid cap-section having s. short skirt-portion received in the connterbore in said main section. said skirt-portion being iengthened at one' eide to bridge the cut-away portion in the rim of thev main section, and a tension-spring mounted on the longer skirt portionof said thread-case cap.

'1. .A stationary thread-case ior rotary hook sewing machines comprising separable main and cap-sections, said main section bein@ cup-shaped and having at its rim an outwardly extending needle-loop guard-ange which is formed at its 4upper portion with rotation-restraining means,

said main section also having a cylindrical inner side wail and a nat inner end wall, a center post carried by said end wall and having a latching groove at its4 free end, said main section also having e. peripheral bearing rib disposed between 20 the plane of said end wall and said needleloop said mainsection being cut away as iar las said peripheral bearing rib and theremeining rimportion being counterboied to an axial depth not exceeding the sng of the peripheral hearing rib from the needle-loop guard-flange, seid capsection having a substantially circular head'reoeived in the counterbore in said mein section, said cap-section head having a cylindrical smitportion at its edge which substantially closes the gap in the rim oi said main section, a tension leaf-spring mounted on the outer side wall of said skirt-portion in said gap with the free end of seid tension-spring 'terminating in seid gap in non-underlapping relation' with. the rim of said main section, and a'manually operable latch 'mounted on said cap-section and engageable with the letching groove in said center post. 

